On Brexit, sooner or later we will have to talk about immigration

The Prime Minister’s approach to the Brexit negotiations appears to involve a new hybrid customs option (the so-called Facilitated Customs Agreement), to possibly accept a supranational court and to stay aligned to the Single Market in goods. In doing so, she hopes to divide the EU’s supposedly indivisible four freedoms and solve the Irish border question. But as ministers gather at Chequers, they should not forget the issue that more than any other in the referendum brought them there – migration.

If the UK wants to align to the Single Market on goods, then Brussels will want to know what that means for services and the other freedoms, and that includes migration. But the future migration policy rarely features in the Brexit debate at the UK at the moment. A clear UK position on post-Brexit migration, once promised for last summer, is now not expected until the Migration Advisory Committee reports in the autumn.

It seems highly unlikely that the EU would sign up to anything like the deal the Prime Minister seems to be proposing while accepting a migration regime that treated EU nationals in the way we treat non-EU nationals now. Assuming the EU is willing to entertain the idea of a ‘goods-only’ deal in the first place, Brussels could try to insist on the continuation of free movement. If Single Market access for services becomes part the discussion, that possibility becomes a certainty. The more the final deal looks like Single Market access, the less negotiable is any departure from freedom of movement.

The UK would have three options on migration

The UK would need to decide what to do next. Its most negotiable option would be to see how far it could get by using existing provisions which the UK has always ignored. Belgium insists that EU citizens who come to the country prove they have a job or enough cash to live off or are studying. The UK does not. That might reduce numbers, but it would not be an end to free movement – and it would scarcely be the promised “taking back control”.

A second approach would be to accept the principle of free movement but seek concessions to allow a customised British deal (what David Cameron tried to do, but he ended up settling for an unsellable package). Switzerland proves an interesting precedent, as a country that has – in essence ‘goods-only’ Single Market access, but which in 2014 struck a deal with the EU to tweak free movement which obliges Swiss firms, in certain circumstances, to show a preference towards Swiss residents.

Finally, there is the question of the "emergency brake" – a "safeguard measure" that can be triggered for unusually high levels of migration causing serious economic, societal or environmental issues. That is the get-out-of-jail clause for proponents of an European Economic Area (EEA)-style agreement who want to end free movement. It’s part of the EEA agreement and has been invoked by Liechtenstein, allowing them to cap the number of migrants.

But it’s unlikely to be a serious long-term solution for the UK. Its existence might reassure some that there is a fallback option; but any brake would only ever be temporary, and persuading the EU27 that it’s necessary for a big economy like the UK, as opposed to a micro-economy like Liechtenstein, would be very difficult. The EU is well briefed on all the academic studies that show that the UK economy benefits from freedom of movement.

If the Government does not come up with a way forward on EU migration after Brexit, it may find it has compromised in vain over regulations and customs. The elephant in the Chequers sitting room may be out of sight – but it will be there nonetheless.